allwinner: CPU drivers should expose pins even if can't expose due to lack of privilege

[maruel]

For example, running i2c-list on a C.H.I.P. as the chip user doesn't print the GPIO lines because the allwinner drive fails to load. It fails to load because it tries to open /dev/mem.

From the user perspective it shouldn't matter, the user can still likely use sysfs gpio support (pending right udev rules) and the pins should still be aliased properly. This means registering the pin aliases when the driver fails to load, which is kind of weird in some ways as a driver failing to load should not have side effects. An option is to split the allwinner driver in two.